Wang and Jiang show that the inherent temporal properties of life motion signals spontaneously engage more intricate brain processings compared with those of nonbiological motions, and consequentially induce subjective time dilation. They thus suggest that the temporal encoding of biological motions relies upon a specialized brain mechanism intrinsically tuned to life motion signals irrespective of their configurations, and is essentially an automatic process operating without a person's awareness.
Point-light biological motions, conveying various different attributes of biological entities, have particular spatiotemporal properties that enable them to be processed with remarkable efficiency in the human visual system. Here we demonstrate that such signals automatically lengthen their perceived temporal duration independent of global configuration and without observers’ subjective awareness of their biological nature. By using a duration discrimination paradigm, we showed that an upright biological motion sequence was perceived significantly longer than an inverted but otherwise identical sequence of the same duration. Furthermore, this temporal dilation effect could be extended to spatially scrambled biological motion signals, whose global configurations were completely disrupted, regardless of whether observers were aware of the nature of the stimuli. However, such an effect completely disappeared when critical biological characteristics were removed. Taken together, our findings suggest a special mechanism of time perception tuned to life motion signals and shed new light on the temporal encoding of biological motion.